This invention relates generally to a method and apparatus for measurement of power output of one powering a system driven by an elongate flexible member such as chain. The system preferably is a bicycle. More specifically, it relates to an apparatus and method for the measurement of power output of a bicyclist.
It is often desirable to measure power output of a bicyclist or a rider of other human powered vehicle. Such information is useful both for the casual rider as well as the high performance trainer. A bicyclist can use this information, among other things, to monitor increases in cardiovascular fitness, quantify maximum output and power, optimize pedaling cadence, and determine maximum efficiency. Such measurements are also useful to those seeking to reduce body fat though exercise or to replenish food during extended rides. While power measuring devices are available on stationary exercise equipment commonly found in health clubs and the like, the size of currently available power measuring devices makes it impractical to install them on actual human powered vehicles. Some force and power measurement equipments use strain gage sensors installed on the crank or the pedal of a bicycle. This attaching typically by gluing must be done carefully with special instructions. The sensor also needs calibration after attaching. One presented way to measure power is also done by sensoring the shoe of a bicyclist. This is not, however, practical in every day use.
In addition to human powered vehicles, power measurements would also be useful for motor driven devices. For example, in motor assisted bicycles, chain tension and/or human power output can be used to determine the relative instantaneous output of the motor. For motor-driven devices such as motorcycles, chain tension and power output can be used to monitor the load on the engine, which relates information on fuel consumption, mechanical wear, and efficiencies.
What is needed then, is a method and device which is compact in size and operatively arranged to measure power output of a bicyclist. Other quite necessary needs are that sensor unit can be easily attached and signal to be measured is easy to find with a good signal to noise ratio. On the other hand a measurement device could be taken to use without a difficult calibration procedure.
The invention broadly provides a method and apparatus for measuring the power output of one powering a bicycle or other system driven by an elongate flexible member. In a preferred embodiment described, the vehicle is a bicycle.
The method of the invention comprises measuring the speed and vibration of the elongate flexible member and calculating the power output therefrom. The apparatus of the invention includes a speed sensor, a vibration sensor, and electronic processing means to calculate and display the power output based upon the measurements made relating to elongate flexible member.
An apparatus for measuring the power transmitted by an elongate flexible member in this invention comprises vibration sensor that measures the vibration frequency of the elongate flexible member, a sensor that directly or indirectly measures the speed of the elongate flexible member; and a computer that determines the power transmitted by the elongate flexible member by receiving the vibration measurement and the speed measurement directly or indirectly measured.
A method for measuring the power transmitted by an elongate flexible member in this invention comprises the steps of measuring the vibration frequency of the elongate flexible member, directly or indirectly measuring the speed of the elongate flexible member, and receiving the vibration measurement and the directly or indirectly measured speed measurement in a computer, and finally generating therefrom a signal representing the power transmitted by the elongate flexible member. In another embodiment, a method for determining the tension in a elongate flexible member on a vehicle such as a bicycle driven by the elongate flexible member comprises the steps of identifying a vibrating section of the elongate flexible member, providing a vibration sensor on the vehicle in proximity to the vibrating section of the elongate flexible member, measuring the frequency of vibration of the vibrating section of the elongate flexible member by means of the sensor during operation of the vehicle, and utilizing the frequency of vibration and the known length of the vibrating section of the elongate flexible member to determine the tension in the elongate flexible member.
In another embodiment a method for determining the vibrational frequency of a elongate flexible member on a vehicle such as a bicycle driven by the elongate flexible member comprises providing the vibration signal of the elongate flexible member by means of a vibration sensor in proximity to the elongate flexible member, performing a Fast Fourier Transform on the vibration signal of the elongate flexible member, and heuristically selecting the vibration frequency of the elongate flexible member.
In another embodiment an apparatus for measuring the tension in a elongate flexible member on a vehicle such as a vehicle driven by the elongate flexible member comprises a vibration sensor mounted on the vehicle in proximity to a vibrating section of the elongate flexible member for measuring the frequency of vibration of the vibrating section of the elongate flexible member during operation of the vehicle, signal processing means on the vehicle operatively connected to the vibration sensor for selecting a measured frequency of vibration, and computer means on the vehicle operatively connected to the signal processing means for computing the tension in the elongate flexible member.
In another embodiment, a method for measuring the power output of a person operating a vehicle such as a bicycle driven by means including a elongate flexible member comprises the steps of measuring the vibration of the elongate flexible member by means of a sensor on the vehicle, measuring directly or indirectly the speed of the elongate flexible member by means of a sensor on the vehicle, computing the power transmitted by the elongate flexible member by means of a computer on the vehicle using the directly or indirectly measured speed of the elongate flexible member and the vibration of the elongate flexible member.
In another embodiment, apparatus for measuring the power output of a person operating a vehicle such as a bicycle driven by means including a elongate flexible member comprises a vibration sensor mounted on the vehicle in proximity to a vibrating section of the elongate flexible member for measuring the vibration frequency of the elongate flexible member, a sensor mounted on the vehicle in proximity to the elongate flexible member for directly or indirectly measuring the speed of the elongate flexible member; and a computer on the vehicle and operatively connected to the vibration sensor and to the sensor which directly or indirectly measures the speed, said computer computing the power transmitted by the elongate flexible member using the measured vibration and directly or indirectly measured speed of the elongate flexible member.
In another embodiment, a method for measuring the power transmitted by an elongate flexible member the method comprising the steps of measuring directly or indirectly the speed variation of the elongate flexible member, and receiving the direct or indirect speed variation measurement in a computer, generating a signal representing the power transmitted by the elongate flexible member. In this embodiment vibration measurement is not been but speed variation measurement is used.
In another embodiment similar to above, an apparatus for measuring the power transmitted by an elongate flexible member comprises a system having a first engagement means separated from a second engagement means, the elongate flexible member coupling the first engagement means with the second engagement means so that when the first engagement means is rotated by a power source the elongate flexible member moves in the direction of the rotation of the first engagement means, which in turn causes the moving elongate flexible member to rotate the second engagement means, sensor that directly or indirectly measures the speed variation of the elongate flexible member; and a computer that determines the power transmitted by the elongate flexible member by receiving the vibration measurement and the speed variation measurement directly or indirectly measured. In this embodiment vibration measurement is not been but speed variation measurement is used.
The primary object of the invention is to provide a method and apparatus for measuring the power output of one powering a chain driven vehicle. The advantages of this invention are simple easy to install sensor units avoiding complex calibration process and however accurate and reliable force and power measurement. Another object of the invention is to display power output of a bicyclist in real time as the cyclist is riding.
These and other objects, advantages and features of the invention will become obvious to those having ordinary skill in the art upon a reading of the following detailed description, read in conjunction with the drawings.